CN111871392A

CN111871392A - Preparation method of chitosan-based gadolinium ion imprinting material

Info

Publication number: CN111871392A
Application number: CN202010709549.3A
Authority: CN
Inventors: 郑旭东; 卞婷婷; 张雨哲; 李忠玉
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2020-07-22
Filing date: 2020-07-22
Publication date: 2020-11-03
Anticipated expiration: 2040-07-22
Also published as: CN111871392B

Abstract

The invention discloses a preparation method of a chitosan-based gadolinium ion imprinted material, which comprises the steps of taking chitosan as an imprinted carrier, performing functionalization treatment on the surface of a carbon nano tube by using polydopamine, then connecting imprinted chitosan, and finally reacting with graphene oxide to obtain the chitosan-based gadolinium ion imprinted material. The chitosan-based gadolinium ion imprinted material prepared by the invention can be used as an adsorbent for adsorbing gadolinium ions in water, and not only has good selective adsorption performance, but also the material is easy to separate and recover from water.

Description

Preparation method of chitosan-based gadolinium ion imprinting material

Technical Field

The invention belongs to the technical field of surface ion imprinted material preparation, and particularly relates to a preparation method of a chitosan-based gadolinium ion imprinted material.

Background

Gadolinium, which is an ion having the largest number of unpaired electrons in rare earth elements, is more stable than other rare earth elements in dry air, unlike other rare earth elements. Gadolinium compounds have high paramagnetism and can be used as a projection agent for magnetic resonance imaging. The special property that gadolinium can adsorb a magnet after being cooled in ice water and can be separated from the magnet after being warmed up makes gadolinium widely applied to the magnetic refrigeration industry. Gadolinium is also widely used in the fields of optical fibers and nuclear energy.

Chitosan is a linear polysaccharide obtained by deacetylation of chitin, and the surface of the chitosan contains groups with strong reactivity of amino and hydroxyl. Therefore, it has the performances of biodegradability, biocompatibility, antibiosis, anticancer, lipid reduction, adsorption and the like. The active group on the surface of the chitosan enables the chitosan to be subjected to diversified chemical modification, so that the chitosan has wide application prospects in various fields such as food, paper making, textile, medical treatment, water treatment and the like.

However, the chitosan is in a powdery form, and the powder is not beneficial to recycling in the application process of the adsorption field. And the unmodified chitosan is easy to agglomerate, has no good specific surface area, and the adsorption sites on the surface do not exert the effect thereof, thereby seriously influencing the adsorption capacity. The existing gadolinium ion imprinting material has good selectivity, but low adsorption capacity and low efficiency in practical application.

Disclosure of Invention

The invention aims to provide a preparation method of a chitosan-based gadolinium ion imprinted material, and the gadolinium ion imprinted material prepared by the method has good selective adsorption effect, good mechanical properties and easy separation and recovery.

The preparation method of the chitosan-based gadolinium ion imprinted material provided by the invention is characterized in that a carbon nano tube is used as a carrier material, polydopamine is firstly utilized for surface amination modification, then the polydopamine is crosslinked with imprinted chitosan, gadolinium ions are eluted by acid, and finally the polydopamine-based gadolinium ion imprinted material reacts with graphene oxide to prepare the composite imprinted material in an aerogel form.

Wherein, the carbon nano tube is a carboxylated carbon nano tube, and the surface of the carbon nano tube is provided with more carboxyl groups. The literature reports various methods for preparing carboxylated carbon nanotubes, and the carboxylated carbon nanotubes prepared by the methods are all suitable for the invention and can be used as the carrier material of the invention.

Specifically, the invention provides a more detailed preparation method of the chitosan-based gadolinium ion imprinting material.

1) Uniformly dispersing the carboxylated carbon nano tube (MWCNT-COOH) into water by ultrasonic waves, then adding dopamine hydrochloride, and fully and uniformly mixing.

Wherein the mass ratio of MWCNT-COOH to dopamine hydrochloride is 1: 1.6-2.5.

2) Adjusting the pH value of the mixed solution in the step 1) to 8-8.5 by using Tris-HCl, separating the modified carbon nano tube and water by using a centrifugal machine after stirring, and respectively washing the carbon nano tube and the water by using ultrapure water and ethanol for three times to remove redundant impurities and unreacted substances; dialyzing the modified carbon nanotubes in water with a dialysis bag with molecular weight of 8000-12000D. After dialysis, the mixture was frozen in a refrigerator overnight and freeze-dried to obtain polydopamine modified carbon nanotubes (MWCNT-PDA).

3) Dissolving Chitosan (CS) in glacial acetic acid solution, stirring and mixing uniformly, and adding Gd (NO)₃)₃Adding into the above solution, and stirring vigorously to mix them uniformly.

Wherein the concentration range of acetic acid in water is 1-2% V/V; chitosan with Gd (NO)₃)₃The mass ratio of (1): 0.25-1.

4) Adding MWCNT-PDA into the solution, uniformly dispersing, and adjusting the pH of the solution to 6.5-7.5 by using NaOH; subsequently heated to 60-70 ℃ and glutaraldehyde is added to the solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having a pH of 3.5 to 4.5 to remove unreacted chitosan.

Wherein the mass ratio of the chitosan to the MWCNT-PDA is 1: 1-1.5; the mass-volume ratio of the chitosan to the cross-linking agent glutaraldehyde is 2:5-10 g/mL.

5) The product was finally washed with acid for 2 weeks to remove the imprinted Gd (iii) sufficiently. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

The acid for washing Gd (III) is a mixed solution of hydrochloric acid and alcohol in a volume ratio of 1: 8-9.

6) And (3) taking Graphene Oxide (GO) with a certain concentration and MWCNT-PDA-CS for ultrasonic dispersion, carrying out oil bath reaction on the mixed solution for a period of time, and then putting the mixed solution into a mold for cooling. Then freezing and drying to obtain MWCNT-PDA-CS-GO.

Wherein the mass ratio of the graphene oxide to the MWCNT-PDA-CS is 200: 35-50. The reaction temperature is 90-100 ℃, and the reaction time is 12 h.

According to the chitosan-based gadolinium ion imprinting material prepared by the invention, due to active groups such as chitosan, polydopamine and amino and hydroxyl on the surface of graphene oxide, the prepared imprinting material is ensured to have good selective adsorption capacity, and the aerogel structure of the graphene oxide is convenient for subsequent separation and recovery.

According to the chitosan-based gadolinium ion imprinting material, the carboxylated carbon nanotube is used as an intermediate carrier, the imprinting function of chitosan and the active functional group of polydopamine are utilized and the lamellar structure and the hydroxyl functional group on the surface of graphene oxide are combined, and the acid solution selected for eluting ions can elute metal ions more quickly than other elution solutions. A series of surface modification, graft polymerization, cross-linking imprinting and elution treatments are carried out on the composite material, so that the chitosan-based gadolinium ion imprinting material prepared by the invention has good selective adsorption performance on gadolinium ions, and on the other hand, the problem of poor mechanical strength of the composite material is solved, the chitosan-based gadolinium ion imprinting material is convenient to recycle, and a new thought is provided for selective gadolinium extraction of the imprinting material.

Drawings

FIG. 1 is a structural morphology diagram of a chitosan-based gadolinium ion imprinted material in example 2;

FIG. 2 is an infrared image of a chitosan-based gadolinium ion imprinted material of example 2;

FIG. 3 is a BET adsorption and desorption curve of a chitosan-based gadolinium ion imprinted material in example 2.

Detailed Description

The following examples are only preferred embodiments of the present invention and are not intended to limit the present invention in any way. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Example 1

80mg of acidified carbon nanotubes (MWCNT-COOH) were ultrasonically and uniformly dispersed in 200ml of water, followed by addition of 200mg of dopamine hydrochloride. After the solutions were mixed well, the pH of the solution was adjusted to 8.5 with Tris-HCl and stirred at 25 ℃ for 48 h. And (3) separating the modified carbon nano tube from the aqueous solution at the rotating speed of 4000rpm by using a centrifugal machine, and washing the carbon nano tube and the aqueous solution for three times by using water and ethanol respectively to remove redundant impurities. The modified carbon nanotubes were then dialyzed in water for 1 week using a dialysis bag with a molecular weight of 8000D. Dialyzing, freezing at-20 deg.C overnight in refrigerator, and lyophilizing to obtain (MWCNT-PDA).

Dissolving 0.2g Chitosan (CS) in 200mL glacial acetic acid with concentration of 1% V/V, stirring and mixing well, adding 0.05g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.2g MWCNT-PDA was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 0.5mL of glutaraldehyde are added to the 60 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. Finally, the product was washed with 10% hydrochloric acid by mass for 2 weeks to sufficiently remove imprinted gadolinium ions. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

Taking 100mL of graphene oxide with the concentration of 2mg/mL and 0.038g of MWCNT-PDA-CS, and carrying out ultrasonic treatment for 1h to uniformly disperse the solution. The mixed solution is put into a die to be cooled after being subjected to oil bath for 12 hours at 90 ℃. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-PDA-CS-GO.

Example 2

90mg of acidified carbon nanotubes (MWCNT-COOH) were ultrasonically and uniformly dispersed in 200ml of water, followed by addition of 200mg of dopamine hydrochloride. After the solutions were mixed well, the pH of the solution was adjusted to 8.5 with Tris-HCl and stirred at 25 ℃ for 48 h. And (3) separating the modified carbon nano tube from the aqueous solution at the rotating speed of 4000rpm by using a centrifugal machine, and washing the carbon nano tube and the aqueous solution for three times by using water and ethanol respectively to remove redundant impurities. The modified carbon nanotubes were then dialyzed in water for 1 week using a dialysis bag with a molecular weight of 8000D. Dialyzing, freezing at-20 deg.C overnight in refrigerator, and lyophilizing to obtain (MWCNT-PDA).

Dissolving 0.2g Chitosan (CS) in 200mL glacial acetic acid with concentration of 1.5% V/V, stirring and mixing well, adding 0.1g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.25g MWCNT-PDA was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 0.7mL of glutaraldehyde are added to the 6 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. Finally, the product was washed with 10.5% hydrochloric acid by mass for 2 weeks to sufficiently remove imprinted gadolinium ions. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

100mL of graphene oxide with the concentration of 2mg/mL and 0.045g of MWCNT-PDA-CS are taken to be ultrasonically treated for 1h to uniformly disperse the solution. And (3) putting the mixed solution into a die for cooling after being subjected to oil bath at 95 ℃ for 12 hours. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-PDA-CS-GO.

The morphology of the aerogel can be clearly seen from fig. 1, and the lamellar structure of the graphene oxide is perfectly represented. Freeze-drying additionally aids in solid-liquid phase separation and also in completing the lamellar honeycomb aerogel morphology. In addition, the modified carbon nanotubes attached to the surface of the graphene oxide sheet layer help to modify the surface, and the hollow structure of the carbon nanotubes helps to increase the specific surface area of the material.

FIG. 2 shows that the chitosan-based gadolinium ion imprinted material is at 4000-500cm^-1The visible peaks within the range are similar. At about 3423cm^-1The absorption peak at (A) is due to-NH₂And stretching vibration of-OH. About 2924 and 2853cm^-1The unique absorption peaks generated at the position are all formed by-CH, -CH₂and-CH₃Is caused by the stretching vibration of (2). At about 1629cm^-1The absorption peak at (A) is due to the presence of-NH at-NH₂Bending vibration in (1). Stretching vibration of C ═ O in N-acetyl group at about 1735, 1718 and 1440cm^-1Causing a distinct absorption peak. At about 1055cm^-1The absorption peak at (a) is due to stretching vibrations at the C-O-C bridge.

FIG. 3 shows a diagram of chitosan-based gadoliniumN of ion imprinted material₂According to the adsorption-desorption isotherm diagram, the isotherm type of the chitosan-based gadolinium ion imprinted material belongs to type IV, and the material with a macroporous structure can be obviously seen. Adsorption hysteresis loops occur between 0.6 and 1.0 at P/P0 due to capillary condensation that occurs with porous adsorbents. After capillary condensation fills, the interactions of the macropores may continue to form multi-layer adsorption.

Example 3

100mg of acidified carbon nanotubes (MWCNT-COOH) were ultrasonically and uniformly dispersed in 200ml of water, followed by addition of 200mg of dopamine hydrochloride. After the solutions were mixed well, the pH of the solution was adjusted to 8.5 with Tris-HCl and stirred at 25 ℃ for 48 h. And (3) separating the modified carbon nano tube from the aqueous solution at the rotating speed of 4000rpm by using a centrifugal machine, and washing the carbon nano tube and the aqueous solution for three times by using water and ethanol respectively to remove redundant impurities. The modified carbon nanotubes were then dialyzed in water for 1 week using a dialysis bag with a molecular weight of 8000D. Dialyzing, freezing at-20 deg.C overnight in refrigerator, and lyophilizing to obtain (MWCNT-PDA).

Dissolving 0.2g Chitosan (CS) in 200mL glacial acetic acid with concentration of 2% V/V, stirring and mixing well, adding 0.2g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.3g MWCNT-PDA was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 1mL of glutaraldehyde are added to the 60 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. Finally, the product was washed with 11% by mass hydrochloric acid for 2 weeks to sufficiently remove imprinted gadolinium ions. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

Taking 100mL of graphene oxide with the concentration of 2mg/mL and 0.05g of MWCNT-PDA-CS, and carrying out ultrasonic treatment for 1h to uniformly disperse the solution. The mixed solution is put into a die to be cooled after being subjected to oil bath for 12 hours at 100 ℃. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-PDA-CS-GO.

Comparative example 1

0.2g of Chitosan (CS) was dissolved in 200mL of 1.5% V/V glacial acetic acid and mixed well by vigorous stirring for 2 h. Then 0.25g MWCNT-PDA was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 0.7mL of glutaraldehyde are added to the 60 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

100mL of graphene oxide with the concentration of 2mg/mL and 0.045g of MWCNT-PDA-CS are taken to be ultrasonically treated for 1h to uniformly disperse the solution. And (3) putting the mixed solution into a die for cooling after being subjected to oil bath at 95 ℃ for 12 hours. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-PDA-CS-GO-N.

Comparative example 2

Taking 100mL of graphene oxide with the concentration of 2mg/mL and 0.045g of MWCNT-PDA to perform ultrasonic treatment for 1 hour to uniformly disperse the solution. And (3) putting the mixed solution into a die for cooling after being subjected to oil bath at 95 ℃ for 12 hours. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-PDA-GO.

Comparative example 3

Dissolving 0.2g Chitosan (CS) in 200mL glacial acetic acid with concentration of 1.5% V/V, stirring and mixing well, adding 0.1g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.25g MWCNT-COOH was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 0.7mL of glutaraldehyde are added to the 60 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. After washing, the MWCNT-CS was placed in an oven at 60 ℃ and dried overnight.

Taking 100mL of graphene oxide with the concentration of 2mg/mL and 0.045g of MWCNT-CS to perform ultrasonic treatment for 1h to uniformly disperse the solution. And (3) putting the mixed solution into a die for cooling after being subjected to oil bath at 95 ℃ for 12 hours. Then freezing at-20 ℃ overnight and freeze-drying at-60 ℃ for 48h to obtain MWCNT-CS-GO.

Comparative example 4

Dissolving 0.125g Chitosan (CS) in 200mL glacial acetic acid with concentration of 1.5% V/V, stirring and mixing well, adding 0.1g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.25g MWCNT-PDA was added and dispersed homogeneously, the pH of the solution was adjusted to 7 with 0.1mol/L NaOH and subsequently heated to 60 ℃ and 0.5mL glutaraldehyde was added to the 6 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. Finally washing the product with 10.5% hydrochloric acidFor 2 weeks to remove fully imprinted gadolinium ions. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

Comparative example 5

Dissolving 0.2g Chitosan (CS) in 200mL glacial acetic acid with concentration of 1.5% V/V, stirring and mixing well, adding 0.1g Gd (NO)₃)₃The solution is stirred vigorously for 2 hours to be mixed evenly. Then 0.15g MWCNT-PDA was added and dispersed uniformly, and the pH of the solution was adjusted to 7 with 0.1mol/L NaOH. Subsequently heated to 60 ℃ and 0.7mL of glutaraldehyde are added to the 6 ℃ solution for crosslinking. The crosslinked mixed solution was separated by filtration, and the filtered product was washed with glacial acetic acid having pH 4 to remove unreacted chitosan. Finally, the product was washed with 10.5% hydrochloric acid by mass for 2 weeks to sufficiently remove imprinted gadolinium ions. After washing, the mixture was placed in an oven at 60 ℃ and dried overnight to give MWCNT-PDA-CS.

Comparative example 6

Application example

The chitosan-based gadolinium ion imprinting material is applied to adsorption of trivalent heavy metal Gd, and the specific method comprises the following steps:

(1) pH: 10mg of the adsorbent was immersed in stock solutions of Gd (10mL,50mg L) at pH 2.0,3.0,4.0,5.0,6.0,6.5 and 7.0, respectively^-1) Reaction time 24h, the final concentration of Gd (III) was determined (by atomic emission spectroscopy). For the pH adjustment of Gd (III) in the experiments 0.1M NaOH and 0.1M HCl solution was used.

(2) Adsorption kinetics: 10mg of the adsorbent were immersed in 10ml of a stock solution of Gd (III) (50mg L) at 298K^-1pH 6.5). The experiment is carried out after the contact time is 1-1440 min. The residual concentration of Gd (III) was determined by atomic emission spectroscopy.

(3) Adsorption isotherm: 10mg of the adsorbent was immersed in stock solutions (10ml, pH 7.0) of Gd (III) at concentrations of 10,25,50,100,150 and 200mg L, respectively^-1. The residual concentration was detected by an atomic emission spectrometer.

(4) Adsorption thermodynamics: 10mg of adsorbent was immersed in 10ml of stock Gd (III) solution (50mg L)^-1pH 7.0) for 24h, the reaction temperature was 298,308 and 318K, respectively. The residual concentration was detected by an atomic emission spectrometer.

(5) Competitive adsorption: preparing four concentrations of Gd (III), Dy (III), Nd (III) and Pr (III) which are all 50mg L^-1The ion mixed solution of (3) was immersed in 10ml of the above mixed solution (pH 7.0) under 298K to react for 24 hours. And finally detecting the residual concentration by an atomic emission spectrometer.

(6) And (3) repeatability experiment: stock solutions of 50mg L at pH 7.0,298K and Gd (III)^-1The films reacted under the conditions were collected, eluted completely with an acid solution, adsorbed under the same conditions, and the residual concentration was measured by atomic emission spectrometry, and the test was repeated 5 times.

The chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 2 has Gd (III) removal amount at pH 2.0,3.0,4.0,5.0,6.0 and 7.0 of 14.53,20.65,22.41,25.53,26.66 and 28.47mg g at equilibrium^-1。

The chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 1 has an adsorption capacity of 28.24mg g at pH 7.0^-1。

The chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 3 has an adsorption capacity of 29.03mg g at pH 7.0^-1。

The adsorption capacity of MWCNT-PDA-CS-GO-N at pH 7.0 was 26.39mg g^-1。

The adsorption capacity of MWCNT-PDA-GO at pH 7.0 is 24.48mg g^-1。

The adsorption amount of MWCNT-CS-GO at pH 7.0 was 25.59mg g^-1。

The adsorption amount of MWCNT-PDA-CS was 20.59mg g at pH 7.0^-1。

The MWCNT-PDA-CS-GO obtained in comparative example 4 adsorbed at pH 7.0 in an amount of 25.08mg g^-1。

Obtained in comparative example 5The adsorption capacity of MWCNT-PDA-CS-GO at pH 7.0 is 25.14mg g^-1。

The dynamics of removing Gd (III) by the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the embodiment 2 are more consistent with the quasi-second order dynamics model (R)²＝0.996)。

The saturated adsorption amount of the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 2 to Gd (III) is 143.85mg g^-1。

The saturated adsorption capacity of the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 1 at pH 7.0 is 138.56mg g^-1。

The saturated adsorption capacity of the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 3 at pH 7.0 is 143.98mg g^-1。

The saturation adsorption capacity of MWCNT-PDA-CS-GO-N at pH 7.0 is 140.78mg g^-1。

The saturation adsorption capacity of MWCNT-PDA-GO at pH 7.0 is 135.85mg g^-1。

The saturation adsorption capacity of MWCNT-CS-GO at pH 7.0 is 138.27mg g^-1。

The saturation adsorption capacity of MWCNT-PDA-CS at pH 7.0 was 135.27mg g^-1。

The MWCNT-PDA-CS-GO obtained in comparative example 4 had a saturated adsorption amount of 137.62mg g at pH 7.0^-1。

The MWCNT-PDA-CS-GO obtained in comparative example 5 had a saturated adsorption amount of 139.21mg g at pH 7.0^-1。

The optimal temperature of the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the above example 2 for Gd (III) adsorption is 318.15K.

The chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the embodiment 2 has specific selective adsorption capacity for Gd (III).

After 5 times of cyclic utilization, the chitosan-based gadolinium ion imprinted material MWCNT-PDA-CS-GO prepared in the embodiment 2 still retains 85% of adsorption capacity.

After 5 times of cyclic utilization, MWCNT-PDA-CS-GO-N retains 81% of adsorption capacity.

After 5 times of recycling, the MWCNT-PDA-GO retains 75% of adsorption capacity.

After 5 times of recycling, the MWCNT-CS-GO retains 74% of adsorption capacity.

After 5 cycles of MWCNT-PDA-CS, 21% of adsorption capacity is retained.

The MWCNT-PDA-CS-GO obtained in comparative example 4 retains 68% of adsorption capacity after 5 cycles.

The MWCNT-PDA-CS-GO obtained in the comparative example 5 retains 59% of the adsorption capacity after 5 times of recycling.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A preparation method of a chitosan-based gadolinium ion imprinting material is characterized by comprising the following steps: the preparation method comprises the following steps: the carbon nano tube is used as a carrier material, firstly, polydopamine is utilized for surface amination modification, then, the carbon nano tube is crosslinked with imprinted chitosan, gadolinium ions are eluted by acid, and finally, the carbon nano tube and graphene oxide react to prepare the composite imprinted material in the form of aerogel.

2. The method for preparing the chitosan-based gadolinium ion imprinted material according to claim 1, characterized in that: the preparation method comprises the following steps:

1) uniformly dispersing the carboxylated carbon nanotube (MWCNT-COOH) into water by ultrasonic waves, then adding dopamine hydrochloride, and fully and uniformly mixing;

2) adjusting the pH value of the solution in the step 1) to 8-8.5 by using Tris-HCl, separating the modified carbon nano tube and water by using a centrifugal machine after stirring, and respectively washing the carbon nano tube and the water by using ultrapure water and ethanol for three times to remove redundant impurities and unreacted substances; dialyzing the modified carbon nano tube in water by using a dialysis bag with the molecular weight of 8000-12000D, freezing overnight in a refrigerator after dialysis, and freeze-drying to obtain a polydopamine modified carbon nano tube (MWCNT-PDA);

3) dissolving Chitosan (CS) in glacial acetic acid solution, stirring and mixing uniformly, and adding Gd (NO)₃)₃Adding the mixture into the solution, and stirring vigorously to mix the mixture evenly;

4) adding MWCNT-PDA into the solution obtained in the step 3), uniformly dispersing, and adjusting the pH of the solution to 6.5-7.5 by using NaOH; then heating to 60-70 ℃, and adding glutaraldehyde into the solution to achieve the purpose of crosslinking;

5) filtering and separating the cross-linked mixed solution, and washing the filtered product with glacial acetic acid with the pH value of 3.5-4.5 to remove unreacted chitosan; the product was washed with acid for 2 weeks to sufficiently remove the imprinted Gd (iii); after washing, putting the mixture into an oven at 60 ℃ and drying the mixture overnight to obtain MWCNT-PDA-CS;

6) taking Graphene Oxide (GO) and MWCNT-PDA-CS to be dispersed uniformly by ultrasonic; after the mixed solution is subjected to oil bath reaction, filling the mixed solution into a mold for cooling; then freezing and drying to obtain MWCNT-PDA-CS-GO.

3. The method for preparing the chitosan-based gadolinium ion imprinted material according to claim 2, characterized in that: the mass ratio of the MWCNT-COOH to the dopamine hydrochloride is 1: 1.6-2.5.

4. The method for preparing a chitosan-based gadolinium ion imprinted material according to claim 2, wherein the chitosan is doped with Gd (NO)₃)₃The mass ratio of (A) to (B) is 1: 0.25-1; the concentration range of acetic acid in water is 1-2% V/V.

5. The method for preparing a chitosan-based gadolinium ion imprinted material according to claim 2, wherein the mass ratio of the chitosan to the MWCNT-PDA is 1: 1-1.5.

6. The preparation method of the chitosan-based gadolinium ion imprinted material according to claim 2, wherein the mass volume ratio of the chitosan to the cross-linking agent glutaraldehyde is 2:5-10 g/mL.

7. The method for preparing a chitosan-based gadolinium ion imprinted material according to claim 2, wherein the acid for washing Gd (III) is a mixed solution of hydrochloric acid and alcohol at a volume ratio of 1: 8-9.

8. The method for preparing a chitosan-based gadolinium ion imprinted material according to claim 2, wherein the mass ratio of the graphene oxide to the MWCNT-PDA-CS is 200: 35-50.

9. The method for preparing a chitosan-based gadolinium ion imprinted material according to claim 2, wherein the reaction temperature is 90-100 ℃ and the reaction time is 12 h.

10. A chitosan-based gadolinium ion imprinted material prepared according to the method of claims 1-9.